1. Field of the Invention
The present invention relates to an accidental erasing preventive device provided in a tape recorder, and more particularly to an accidental erasing preventive device provided in a cassette tape recorder, for preventing accidental erasure of recorded signals on a tape contained in a tape cassette.
2. Description of Prior Art
There is provided in a cassette tape recorder an accidental erasing preventive device which detects the presence of an accidental erasing lock-out tab removably or separably disposed in a tape cassette when the latter is loaded in the cassette tape recorder, so as to control a recording circuit arranged in the cassette tape recorder.
There has been used an accidental erasing preventive device of this kind for a cassette tape recorder, including an accidental erasing preventive lever disposed opposite to an accidental erasing lock-out tab of a tape cassette loaded in a cassette compartment of the cassette tape recorder, the accidental erasing preventive lever being rotatable in a plane parallel to the bottom surface of the cassette compartment; a resilient member such as for example a coil spring, biasing the accidental erasing preventive lever toward the accidental erasing lock-out tab so that the lever abuts against the latter; and a recording circuit control switch disposed in the vicinity of the accidental erasing preventive lever so as to be actuated in response to rotation of the accidental preventive lever.
In such a conventional accidental erasing preventive device, when a tape cassette having accidental erasing lock-out tabs is loaded in the cassette compartment from the top of the latter, the accidental erasing preventive lever is forced, by the tape cassette, to rotate in the direction of overcoming the biasing force of the coil spring so that the accidental erasing preventive lever is withdrawn and then abuts against one of the accidental erasing lock-out tabs. Accordingly, the rotation of the accidental erasing preventive lever causes the recording circuit control switch to be turned, for example "OFF" so as to energize the recording circuit. When a cassette tape recorder with no accidental erasing lock-out tabs is loaded in the cassette compartment from the top of the cassette compartment, the accidental erasing preventive lever is transiently forced, by loading of the tape cassette, to rotate so as to move in the direction of overcoming the biasing force of the coil spring in a manner similar to that mentioned above. However, the biasing force of the coil spring returns the accidental erasing preventive lever until the latter enters into the tape cassette through one of the notches opened by the separation of the accidental erasing lock-out tabs, when the detecting end of the accidental erasing preventive lever is facing the notch. Therefore, the accidental erasing preventive lever is brought to the original position. Accordingly, the return of the lever allows the recording circuit control switch to be turned "ON" so as to hold the recording circuit deenergized, whereby accidental erasure of recorded signals is prevented.
In the above-mentioned conventional arrangement of the accidental erasing preventive device in which the accidental erasing preventive lever is rotated in a plane parallel to the bottom surface of the cassette compartment, that is, substantially orthogonal to the direction of the tape cassette loaded from the top of the compartment, it is disadvantageous that stable and reliable operation of accidental erasure protection cannot be expected, since the rotational direction of the accidental erasing preventive lever is completely different from the direction of the tape cassette insertion or loading which exerts unreasonable force on the lever so that not only smooth operation of the lever is hindered but also the lever is possibly damaged.
Further, the provision of the independent recording circuit control switch in the close vicinity of the accidental erasing preventive lever, which responds to the rotation of the latter, interferes with ultraminiaturization and cost reduction in cassette tape recorders, which are a recent trend, due to provision of a space for the switch to occupy and due to increase in the number of necessary parts for assembling the cassette tape recorders.